1. Field of the Invention
The present invention relates, in general, to systems and methods of medical pain management and, more particularly, to the management of pain and discomfort associated with endoscopies.
2. Description of the Related Art
Endoscopy is a term used to describe medical procedures involving the use of an endoscope, where an endoscope is an instrument for examining visually the interior of a bodily cavity or a hollow organ such as the colon, bladder, or stomach. Endoscopic procedures include colonoscopies, esophagogastroduodenoscopies (EGDs), and other visually invasive procedures, where a number of fiber optic and video chip endoscopes have been specifically designed and adapted to particular areas of operation.
Colonoscopies and other procedures involving the insertion of an endoscope into the colon of a patient are generally performed using sedation administered intravenously with medications such as benzodiazepine sedatives (Midazolam) and/or opioid narcotic analgesics (Fentanyl). Undesirable effects of IV sedation drugs for a patient may include, among others, respiratory depression, missed work due to time of recovery from drug effect, and anaphylaxis or other allergic reactions. The pain and discomfort of endoscopies are generally attributable to the stimulation of pain sensitive nerve endings found in the mucous membranes of the gastrointestinal tract. In attempts to alleviate the pain and discomfort in the absence of sedatives, oral and rectal local anesthetic sprays have been developed that deliver lidocaine and other local anesthetic agents to a particularly sensitive region. These agents may have only a nominal affect on the pain and discomfort experienced by the patient as the endoscope is driven farther into the gastrointestinal tract.
Colonoscopy is a generic term describing the common procedure employed in examining the colon with a fiber optic system which is known as a colonoscope. The colonoscope is also used in removing polyps and other tissue in the colon for diagnostic and other purposes.
During an examination, the colonoscope (or endoscope) is driven into the rectum, through the sigmoid colon and the descending colon into the splenic flexure. At this point, the scope must be manipulated through a ninety-degree bend to enter the transverse colon. While colonoscopes generally have a steerable or bendable head, the force necessary to progress the colonoscope across the splenic flexure can only be applied by pushing the colonoscope from outside the anus in a direction at right angles to the desired direction of travel. After the colonoscope has moved through the transverse colon, the colonoscope encounters the hepatic flexure, another ninety-degree turn leading to the ascending colon. To steer the scope down the ascending colon toward the caecum, force applied to the portion of the colonoscope located near the anus of the patient must vector through a minimum of two right angle bends.
The manipulations used to move the colonoscope through the rectum and colon may be extremely painful and uncomfortable to the patient due to the nerve endings in the colon located in the mucosal and muscular walls. The principal forces to which these nerves are sensitive are stretching and tension, both of which occur when the relatively rigid colonoscope passes through the colon. In general, the only existing means of relieving the pain and discomfort that result from the stretching, torsion, and friction incurred during a colonoscopy is to provide sedation and analgesia to the patient, an often undesirable alternative since the drug levels required to relieve the discomfort often render the patient unable to cooperate during the procedure.
In the past, attempts have been made to make endoscopic devices such as gastric tubes and catheters pass more easily through tubular body structures by coating them with polymers having low coefficients of friction. Such coatings must be bonded to the device, either covalently or by other means. These coatings are subject to wear and eventually can lose their effectiveness, particularly when applied to reusable devices such as colonoscopes and cystoscopes. Permanent coatings also must be able to withstand sterilization and/or disinfecting procedures without losing effectiveness, a difficult technical requirement.
Endoscopic devices have also been coated with a petrolatum or water-based lubricant prior to insertion as a means of easing patient discomfort. However, in the case of colonoscopy, these lubricants are often removed from the colonoscope as it is inserted into the rectum and advanced through the anal sphincter. Very little lubricant remains afterwards to ease further manipulation of the colonoscope. Certain existing devices attempt to reduce the amount of lubricant and anesthetic lost during insertion of the colonoscope by employing a syringe or flexible plastic bottle equipped with a long applicator tip to coat the surface of the colonoscope while the colonoscope passes through the rectum. Though such devices may have some effect in reducing the friction coefficient of the colonoscope, much of the lubricant and/or anesthetic may be lost as the colonoscope is pushed farther into the colon. Further, applying the lubricant and/or anesthetic to the colonoscope inside the rectum may make fully coating the scope and fully coating sensitive colon tissue a difficult task.